The following account of the prior art relates to one of the areas of application of the present invention, hearing instruments.
Hearing aids with a so-called open fitting having an ITE-part comprising a receiver located in the ear canal (RITE) and a BTE-part comprising a processing part located behind the ear have become increasingly used. Each BTE-part may be connectable to a number of different ITE-parts. Various methods of identifying and distinguishing these RITE modules have been proposed to ensure that a given combination of BTE- and RITE-modules will not impose damage and/or produce uncomfortable sound levels to the end user (e.g. due to the connection of a RITE module with higher sensitivity or maximum output power than actually intended, e.g. as determined during fitting).
WO 02/11509 describes a hearing device comprising a first module with an electrical supply as well as an electrical to mechanic output converter and a second module with a signal processing unit as well as an acoustical/electrical input converter. In an embodiment, the hearing device comprises a code unit in said first module and a code-reader and decoding unit in said second module.
WO 99/09799 deals with a hearing aid with a central signal processing unit, which interacts with peripheral units on the input and output side. The peripheral units each have an identification unit whose output interacts with the input of a comparing unit. The comparing unit in turn interacts with identification-possibility memory units, and acts on a configuration storage unit on the output side. In this way, the hearing aid configuration can identify itself using the peripheral units.
WO 2007/045254 A1 describes an interchangeable acoustic system for a hearing aid, where the acoustical system is adapted for conducting sound from an output transducer in the hearing aid housing of the hearing aid to an ear of a user, and where the interchangeable acoustic system comprises an encoding indicating acoustical properties of the interchangeable acoustic system. In an embodiment, the interchangeable acoustic system comprises an adapter for attaching the interchangeable acoustic system to a hearing aid housing of a hearing aid, and wherein said encoding comprises at least one electrically conductive area arranged in connection with the adapter and where the electrically conductive area has a resistance value indicating the acoustical properties of the system.
WO 2009/065742 A1 describes a hearing aid comprising a signal processing device, a receiver connected to the signal processing device and a microphone connected to the signal processing device, whereby the signal processing device is electrically coupled to a connection socket operable to detachably connect the receiver to the socket, and whereby the signal processing device further comprises a detector operable to detect a characteristics of the receiver which is connected to the signal processing device through the connection socket. In an embodiment, a characteristic of the receiver is a characteristic parameter of an additional element included in the receiver, such as a capacitor or a resistor or any other electronic element.
US 2009/00521706 describes a hearing aid system, which comprises an automatic identification of the type of receiver used. Further, automatic adaptation of the signal processing in the hearing aid device is provided according to the type of receiver identified by the hearing aid system. Incorrect manual adaptation is thereby prevented. In an embodiment, different resistors are associated with different types of receivers, and the respective type of receiver used in the hearing aid device is able to be identified by the value of the resistor.